Damper device

ABSTRACT

A damper device includes a first rotor disposed to be rotatable, a second rotor rotatable relative to the first rotor, and a plurality of elastic members configured to elastically couple the first rotor and the second rotor in a circumferential direction. The first rotor includes a first plate and a second plate. The first and second plates are axially opposed to each other, and fixed to be immovable in both axial and circumferential directions. The first plate includes a plurality of first holding portions and a plurality of bent portions. The plurality of first holding portions hold the plurality of elastic members. The plurality of bent portions are provided on an outer peripheral end of the first plate, and bent toward the second plate. The second plate includes a plurality of second holding portions holding the plurality of elastic members together with the plurality of first holding portions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2019-049049, filed Mar. 15, 2019. The contents of that application areincorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a damper device.

BACKGROUND ART

A variety of devices are embedded in a drive train of a vehicle in orderto transmit power generated in an engine to a transmission. For example,a damper device and a flywheel assembly are assumable as this type ofdevices. In order to attenuate rotational vibration, these devices areprovided with such a damper mechanism as described in Japan Laid-openPatent Application Publication No. 2015-161371.

A damper device described in Japan Laid-open Patent ApplicationPublication No. 2015-161371 includes an input plate, an output plate, aplurality of springs (low stiffness springs and high stiffness springs)and an intermediate plate. The output plate is disposed to be rotatablewith respect to the input plate. On the other hand, the intermediateplate is engaged with a plurality of pairs of low stiffness and highstiffness springs, whereby each pair of low stiffness and high stiffnesssprings is coupled in series.

The input plate described in Japan Laid-open Patent ApplicationPublication No. 2015-161371 includes a pair of disc-shaped plates fixedto be immovable relative to each other in both circumferential and axialdirections. The pair of disc-shaped plates is provided with pairs ofwindow portions for holding the pairs of torsion springs in the outerperipheral parts thereof. A torque is transmitted to the pairs oftorsion springs through the pairs of window portions.

As described above, the pair of plates, composing the input plate,transmits the torque through the pairs of window portions, and is alsorotated. Hence, the pair of plates is required to have a large platethickness so as to exert high strength against rotation. This becomes anobstacle in attempt to reduce the axial dimension of the damper device.

BRIEF SUMMARY

It is an object of the present invention to enhance the strength of arotor composed of a pair of plates with a simple configuration.

(1) A damper device according to the present invention includes a firstrotor disposed to be rotatable, a second rotor rotatable relative to thefirst rotor, and a plurality of elastic members elastically coupling thefirst rotor and the second rotor in a circumferential direction. Thefirst rotor includes a first plate and a second plate. The first andsecond plates, each having a disc shape, are disposed in axialopposition to each other and are fixed to be immovable in both axial andcircumferential directions. The first plate includes a plurality offirst holding portions and a plurality of bent portions. The pluralityof first holding portions hold the plurality of elastic members. Theplurality of bent portions are provided on an outer peripheral end ofthe first plate, and are bent toward the second plate. On the otherhand, the second plate includes a plurality of second holding portionsthat hold the plurality of elastic members together with the pluralityof first holding portions.

In the present damper device, power, when inputted to the first rotor,for instance, is transmitted therefrom to the second rotor through theplurality of elastic members held by the first and second holdingportions.

The first rotor herein includes the first and second plates each havinga disc shape. The first plate is provided with the plurality of bentportions in the outer peripheral end thereof, and the second plate isfixed to the first plate. Hence, the first rotor as a whole is enhancedin strength against rotation. Because of this, each plate can be reducedin thickness, whereby the damper device can be reduced in axialdimension.

(2) Preferably, the second rotor is disposed axially between the firstplate and the second plate.

(3) Preferably, the damper device further includes a third rotor. Thethird rotor is rotatable relative to the first rotor and the secondrotor, and actuates at least two of the plurality of elastic members inseries. Besides, preferably, the third rotor is capable of makingcontact in part with at least one of circumferential end surfaces of theplurality of bent portions.

Here, an angle of relative rotation (torsion angle) between the firstplate and the third rotor can be set to fall within a predeterminedangular range by causing the third rotor to make contact with at leastone of the circumferential end surfaces of the plurality of bentportions. In other words, the plurality of bent portions and the thirdrotor can realize a stopper mechanism for restricting the torsion anglebetween the first rotor and the second and third rotors.

(4) Preferably, the third rotor includes an annular portion and aflange. The flange is provided to extend radially outward from theannular portion, and actuates the at least two of the plurality ofelastic members in series. Besides, preferably, the first plate and thethird rotor are restricted from being rotated relative to each otherwhen the flange makes contact at an outer peripheral part thereof withone of the circumferential end surfaces of the plurality of bentportions.

(5) Preferably, the first plate includes a fixation portion. Thefixation portion is formed by bending a distal end of each of theplurality of bent portions radially inward. The damper device furtherincludes a fixation member fixing the fixation portion and the secondplate to each other.

(6) Preferably, each of the first plate and the second rotor includes awork hole for fixing the fixation portion and the second plate to eachother by the fixation member.

(7) Preferably, the second rotor includes a hub having a tubular shape.Besides, preferably, each of the first and second plates includes a holein a center part thereof, and are radially positioned by an outerperipheral surface of the hub and an inner peripheral surface of thehole of the each of the first and second plates.

Overall, according to the present invention described above, it ispossible to enhance the strength of a rotor composed of a pair of plateswith a simple configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a power transmission deviceincluding a damper device according to a preferred embodiment of thepresent invention.

FIG. 2 is a view of a torque limiter device extracted from FIG. 1.

FIG. 3 is a view of the damper device extracted from FIG. 1.

FIG. 4 is a view of a hysteresis generating mechanism shown in FIG. 1.

FIG. 5 is a front view of the damper device shown in FIG. 1, from whichpart of members is detached.

FIG. 6 is an external view of the hysteresis generating mechanism.

FIG. 7 is a chart showing magnitude of vibration attributed to resonanceof an intermediate rotor and magnitude of vibration in the presentpreferred embodiment.

DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view of a power transmission device 1including a damper device according to a preferred embodiment of thepresent invention. FIG. 2 is a front view of the power transmissiondevice 1 that part of members is detached therefrom. The powertransmission device 1 is installed in, for instance, a hybrid vehicle.The power transmission device 1 includes a torque limiter device 2 and adamper device 3 that power generated in an engine is inputted theretothrough the torque limiter device 2. The engine is disposed on the rightside in FIG. 1, whereas an electric motor, a transmission and so forthare disposed on the left side in FIG. 1. In FIG. 1, line 0-0 indicates arotational axis.

[Torque Limiter Device 2]

The torque limiter device 2 is coupled to a flywheel 4 to which thepower generated in the engine is inputted. Additionally, when anexcessive torque is inputted from an output side, for instance, thetorque limiter device 2 limits the magnitude of the excessive torque toa predetermined value or less so as not to transmit the excessive torquetherethrough to the engine. The torque limiter device 2 includes a cover10, a damper plate 11, a friction disc 12, a pressure plate 13 and acone spring 14. The friction disc 12, the pressure plate 13 and the conespring 14 are accommodated in the interior of the cover 10.

FIG. 2 shows an enlarged view of the torque limiter device 2. The cover10 includes a coupling portion 10 a, a tubular portion 10 b and asupport portion 10 c. The coupling portion 10 a, the tubular portion 10b and the support portion 10 c are integrally processed by stamping.Therefore, the tubular portion 10 b is drafted (tapered) by drawing, andthereby slants to the inner peripheral side with separation from theflywheel 4. Additionally, a curved surface portion 12 d is providedbetween the tubular portion 10 b and the support portion 10 c.

The coupling portion 10 a has an annular shape and is coupled to theflywheel 4 by a plurality of bolts 15, while the damper plate 11 isinterposed therebetween. The tubular portion 10 b extends from the innerperipheral end of the coupling portion 10 a to an output side (a sideseparating from the flywheel 4). The support portion 10 c has an annularshape and extends from the distal end of the tubular portion 10 b to theinner peripheral side at a predetermined width. The support portion 10 cis provided with a support protrusion 10 e in a radially intermediatepart thereof. The support protrusion 10 e has an annular shape andprotrudes toward the flywheel 4.

The damper plate 11 has an annular shape and is provided with aplurality of holes 11 a in the outer peripheral part thereof. The damperplate 11 is fixed together with the cover 10 to a lateral surface of theflywheel 4 by the bolts 15 that penetrate the holes 11 a, respectively.The outer diameter of the damper plate 11 is equal to that of theflywheel 4, and the inner diameter thereof is less than that of eachfriction material (to be described) of the friction disc 12.

The friction disc 12 includes a core plate 17 and a pair of frictionmaterials 18. The core plate 17 has an annular shape and is providedwith a plurality of fixation portions 17 a extending from the innerperipheral end thereof further radially inward. The core plate 17 iscoupled to the damper device 3 through the fixation portions 17 a. Thepair of friction materials 18, each having an annular shape, is fixed tothe both lateral surfaces of the core plate 17.

The pressure plate 13 has an annular shape, and is disposed inopposition to the damper plate 11 through the friction disc 12. In otherwords, the friction disc 12 is interposed and held between the damperplate 11 and the pressure plate 13. The inner diameter of the pressureplate 13 is less than that of each friction material 18 of the frictiondisc 12.

The cone spring 14 is disposed between the pressure plate 13 and thesupport portion 10 c of the cover 10, while being compressedtherebetween. The cone spring 14 is supported at the outer peripheralpart thereof by the support protrusion 10 e of the support portion 10 c,and makes contact at the inner peripheral end thereof with the pressureplate 13, whereby the pressure plate 13 is pressed toward the flywheel4.

When a torque, transmitted between the engine side and the damper device3 through the torque limiter device 2 configured as described above,exceeds a torque transmission capacity that is set by the torque limiterdevice 2, slippage occurs in a friction disc 12-related part and thetorque to be transmitted through the torque limiter device 2 is limitedin magnitude.

In this torque limiter device 2, the tubular portion 10 b of the cover10 is drafted (tapered) to the inner peripheral side with separationfrom the flywheel 4. Therefore, the output-side end of the tubularportion 10 b has a smaller inner peripheral surface diameter than theflywheel 4-side end thereof. Additionally, the tubular portion 10 b isprovided with the curved surface portion 12 d on the output-side endthereof. Because of this, when it is assumed to dispose the frictiondisc 12 on the support portion 10 c side, the friction disc 12 cannot bereliably designed to have a large diameter.

However, in the present preferred embodiment, the friction disc 12 isdisposed on the flywheel 4 side in the interior of the cover 10. Hence,the friction disc 12 can be designed to have as large a diameter aspossible without being affected by the draft of the tubular portion 10b. Contrarily speaking, the torque limiter device 2 can be made compactin diameter without changing the torque transmission capacity thereof.

Additionally, in the present preferred embodiment, the friction disc 12is disposed to press the flywheel 4 through the damper plate 11. Now itis assumed, contrarily to the present preferred embodiment, that thefriction disc 12 is disposed on the cover 10 side (the support portion10 c side) whereas the cone spring 14 is disposed on the flywheel 4side. In this assumption, elastic deformation occurs in the supportportion 10 c of the cover 10 such that an inner peripheral part thereofis opened outward. As a result, chances are that relevant one of thefriction materials 18 of the friction disc 12 does not uniformly makecontact with the support portion 10 c, whereby a desired torque capacitycannot be obtained or abnormal abrasion occurs in the relevant frictionmaterial 18. To avoid such troubles, it is required to increase thethickness of a plate member of which the cover 10 is made.

However, in the present preferred embodiment, the friction disc 12 isdisposed on the flywheel 4 side, whereas the cone spring 14 is disposedon the cover 10 side (the support portion 10 c side). Hence, deformationis unlikely to occur in a surface with which the friction disc 12 makescontact (i.e., a lateral surface of the damper plate 11). Therefore, theentirely of relevant one of the friction materials 18 of the frictiondisc 12 uniformly makes contact with the damper plate 11, whereby astable torque capacity can be obtained. Moreover, abnormal abrasion canbe inhibited from occurring in the relevant friction material 18 of thefriction disc 12.

Incidentally, likewise in the present preferred embodiment, elasticdeformation occurs in the support portion 10 c of the cover 10. However,this elastic deformation acts as a force for pressing the friction disc12 together with an urging force of the cone spring 14. Because of this,it is possible to reduce the thickness of the plate member of which thecover 10 is made. Consequently, it is possible to realize compactness inaxial size of the torque limiter device 2.

Moreover, the torque limiter device 2, configured as described above,can be easily attached even to a versatile flywheel, i.e., a flywheelwithout a special shape for attaching a torque limiter.

[Damper Device 3]

The damper device 3 transmits power, inputted thereto from the torquelimiter device 2, to the output side, and attenuates vibration occurringin transmitting the power. FIG. 3 shows the damper device 3 extractedfrom FIG. 1. The damper device 3 includes an input-side rotor 20(exemplary first rotor), an output-side rotor 21 (exemplary secondrotor), a plurality of torsion springs 22, an intermediate rotor 23(exemplary third rotor) and a hysteresis generating mechanism 24.

<Input-Side Rotor 20>

The input-side rotor 20 is rotatable about the rotational axis, andincludes a first plate 31 and a second plate 32.

The first plate 31 includes a disc portion 31 a, a plurality of firstwindow portions 31 b (exemplary first holding portions) for holding thetorsion springs 22, a plurality of bent portions 31 c and a plurality offixation portions 31 d (see FIG. 4). It should be noted that FIG. 4shows a cross-section of the damper device 3, which is taken in acircumferential position different from that in FIG. 1. It should benoted that radial positioning of the first plate 31 is made by the innerperipheral surface of the disc portion 31 a and the outer peripheralsurface of a tubular hub (to be described) of the output-side rotor 21.

The first window portions 31 b are provided in an outer peripheral partof the disc portion 31 a. Each first window portion 31 b includes a holeand holding portions. The hole is circumferentially elongated andaxially penetrates the disc portion 31 a. The holding portions areprovided on the inner and outer peripheral edges of the hole so as tohold the torsion spring 22. The hole is capable of making contact, atthe circumferential end surfaces thereof, with the end surfaces of thetorsion spring 22.

Each bent portion 31 c, having an L-shaped cross-section, is formed bybending the outer peripheral end of the disc portion 31 a toward theflywheel 4. Enhancement in rotational strength of the first plate 31 isrealized by bending the outer peripheral end of the disc portion 31 a inthe cross-sectional L shape.

As shown in FIGS. 4 and 5, each fixation portion 31 d is formed bybending the distal end of a circumferentially middle part of each bentportion 31 c further radially inward. It should be noted that FIG. 5 isa front view of the damper device 3 that part of members is detachedtherefrom. Additionally, each fixation portion 31 d is provided with arivet fixation hole 31 e. It should be noted that a plurality of rivetswaging holes 31 f (exemplary work holes) are provided in the samepositions as the rivet fixation holes 31 e of the disc portion 31 a.

The second plate 32 is disposed in axial opposition to the first plate31 on the flywheel 4 side of the first plate 31. The second plate 32,having a disc shape, includes a plurality of second window portions 32 b(exemplary second holding portions). It should be noted that radialpositioning of the second plate 32 is made by the inner peripheralsurface of the second plate 32 and the outer peripheral surface of thetubular hub (to be described) of the output-side rotor 21.

The second window portions 32 b are provided in corresponding positionsto the first window portions 31 b of the first plate 31. Each secondwindow portion 32 b includes a hole and holding portions. The hole iscircumferentially elongated and axially penetrates the second plate 32.The holding portions are provided on the inner and outer peripheraledges of the hole so as to hold the torsion spring 22. The hole iscapable of making contact, at the circumferential end surfaces thereof,with the end surfaces of the torsion spring 22. Each second windowportion 32 b holds the torsion spring 22 together with each first windowportion 31 b of the first plate 31.

Additionally, the second plate 32 is provided with a plurality of rivetfixation holes 32 e in the same positions as the rivet fixation holes 31e of the first plate 31. The first and second plates 31 and 32 are fixedby a plurality of rivets 33 (exemplary fixation members), penetratingthe pairs of rivet fixation holes 31 e and 32 e of the both plates 31and 32, respectively, so as to be immovable in both axial andcircumferential directions. It should be noted that the first and secondplates 31 and 32 and the friction disc 12 are fixed to each other, whilethe fixation portions 17 a of the core plate 17 in the friction disc 12are inserted in between the fixation portions 31 d of the first plate 31and the second plate 32.

<Output-Side Rotor 21>

The output-side rotor 21 is disposed axially between the first plate 31and the second plate 32. The output-side rotor 21 is rotatable about therotational axis, and is rotatable relative to the first and secondplates 31 and 32. The output-side rotor 21 includes a hub 35 and threeflanges 36.

The hub 35, having a tubular shape, is disposed in the center part ofthe output-side rotor 21. The hub 35 is provided with a spline hole 35 ain the inner peripheral part thereof, and the spline hole 35 a iscoupled to a spline provided on an output-side shaft (not shown in thedrawings). As described above, the first and second plates 31 and 32 areradially positioned with respect to the hub 35 by the outer peripheralsurface of the hub 35 and the inner peripheral surfaces of the first andsecond plates 31 and 32.

The three flanges 36 are provided to radially extend from the outerperipheral surface of the hub 35 in a radial shape. The three flanges 36are disposed at equal angular intervals in the circumferentialdirection. Each flange 36 includes a hysteresis mechanism attachingportion 36 a, a first support portion 36 b and a second support portion36 c. The hysteresis mechanism attaching portion 36 a, made in the shapeof a flat surface, is provided on the outer peripheral side of the hub35. The first support portion 36 b extends radially outward from thehysteresis mechanism attaching portion 36 a, and has a smallercircumferential width than the hysteresis mechanism attaching portion 36a. The first support portion 36 b make contact, at the bothcircumferential end surfaces thereof, with spring seats 38. The secondsupport portion 36 c is formed by circumferentially extending the bothends of the outer peripheral end of the first support portion 36 b. Thesecond support portion 36 c makes contact, at the inner peripheralsurface thereof, with the spring seats 38.

It should be noted that the second support portions 36 c of the flanges36 are disposed in the same radial positions as the fixation portions 31d of the first plate 31. Each second support portion 36 c is providedwith a hole 36 d (exemplary work hole) axially penetrating therethrough.Rivet swaging of the first and second plates 31 and 32 is made throughthe holes 36 d and the rivet swaging holes 31 f of the first plate 31.

<Torsion Springs 22>

The torsion springs 22 are accommodated circumferentially between theplural flanges 36 of the output-side rotor 21 and are held by the firstwindow portions 31 b of the first plate 31 and the second windowportions 32 b of the second plate 32. It should be noted that twotorsion springs 22 are disposed between adjacent two of the flanges 36,and the spring seats 38 are disposed on the both end surfaces of eachtorsion spring 22.

<Intermediate Rotor 23>

The intermediate rotor 23 is rotatable about the rotational axis, and isrotatable relative to the first plate 31, the second plate 32 and theoutput-side rotor 21. The intermediate rotor 23 is a member for causingtwo torsion springs 22, disposed between any adjacent two of the flanges36, to act in series. The intermediate rotor 23 includes an annularportion 40 and three intermediate flanges 41 (exemplary flange).

The annular portion 40 is slid and fitted, at the inner peripheral partthereof, onto the outer periphery of the hub 35 of the output-side rotor21. In other words, the inner peripheral surface of the annular portion40 and the outer peripheral surface of the hub 35 make contact with eachother, whereby the intermediate rotor 23 is radially positioned withrespect to the output-side rotor 21. The annular portion 40 is disposedin axial alignment with the flanges 36 of the output-side rotor 21 onthe flywheel 4 side of the flanges 36.

Each of the three intermediate flanges 41 includes an offset portion 41a, a friction portion 41 b, a first support portion 41 c, a secondsupport portion 41 d and a stopper portion 41 e.

As shown in FIGS. 3 and 5, the offset portion 41 a is a portion thatcouples the annular portion 40 and the friction portion 41 btherethrough. The both lateral surfaces of the friction portion 41 b areherein disposed in the same axial positions as those of each flange 36of the output-side rotor 21. In other words, the flywheel 4-side lateralsurface of the friction portion 41 b and that of each flange 36 of theoutput-side rotor 21 are located on one plane. Likewise, the output-sidelateral surface of the friction portion 41 b and that of each flange 36of the output-side rotor 21 are located on one plane. The offset portion41 a couples therethrough the annular portion 40 and the frictionportion 41 b that are disposed in different axial positions.

The first support portion 41 c extends radially outward from thefriction portion 41 b, and has a smaller circumferential width than thefriction portion 41 b. The first support portion 41 c makes contact, atthe both circumferential end surfaces thereof, with the spring seats 38.The second support portion 41 d is formed by circumferentially extendingthe both ends of the outer peripheral end of the first support portion41 c. The second support portion 41 d makes contact, at the innerperipheral surface thereof, with the spring seats 38.

The stopper portion 41 e is provided on the circumferentially middlepart of the outer peripheral surface of the first support portion 41 c,and protrudes radially outward. The stopper portion 41 e is disposed inthe circumferential middle of adjacent two of the bent portions 31 c ofthe first plate 31. Additionally, the circumferential end surfaces ofthe stopper portion 41 e are capable of making contact with those of theadjacent two bent portions 31 c, respectively.

In other words, the angle of relative rotation between the input-siderotor 20 and the intermediate rotor 23 (furthermore, the output-siderotor 21) is limited to fall within a predetermined angular range byeach stopper portion 41 e of the intermediate rotor 23 and the adjacenttwo bent portions 31 c of the first plate 31.

[Hysteresis Generating Mechanism 24]

The hysteresis generating mechanism 24 is disposed radially between thehub 35 of the output-side rotor 21 and the torsion springs 22. Besides,the hysteresis generating mechanism 24 is disposed axially between thefirst plate 31 and both the flanges 36 (specifically, the hysteresismechanism attaching portions 36 a) of the output-side rotor 21 and theintermediate flanges 41 (specifically, the friction portions 41 b) ofthe intermediate rotor 23, while being disposed axially between thesecond plate 32 and both the flanges 36 of the output-side rotor 21 andthe intermediate flanges 41 of the intermediate rotor 23.

As shown in FIGS. 4 and 6, the hysteresis generating mechanism 24includes two annular disc plates 45, two friction plates 46 and a conespring 47. The two annular disc plates 45 are different from each otheronly in terms of dimension, and this is true of the two friction plates46. Hence, the annular disc plate 45 and the friction plate 46, whichare disposed on the first plate 31 side, will be hereinafter explained.It should be noted that FIG. 6 shows the output-side rotor 21, theintermediate rotor 23 and part of the hysteresis generating mechanism24, which are extracted from the damper device 3.

The annular disc plate 45, having an annular shape, makes contact withthe lateral surface of the output-side rotor 21 and that of theintermediate rotor 23. Additionally, the annular disc plate 45 is fixedto the hysteresis mechanism attaching portions 36 a of the output-siderotor 21. Therefore, the annular disc plate 45 is non-rotatable relativeto the output-side rotor 21, but is rotatable relative to theintermediate rotor 23. It should be noted that albeit not hereindescribed in detail, the annular disc plate 45 is provided with aplurality of fixation portions protruding to the inner peripheral side,for instance, and is fixed at the fixation portions to the output-siderotor 21 by rivets or so forth.

The friction plate 46, having an annular shape, makes contact at theflywheel side lateral surface thereof with the annular disc plate 45,while making contact at the other lateral surface thereof with the firstplate 31. Additionally, the friction plate 46 is provided with aplurality of engaging protrusions 46 a axially protruding from the firstplate 31-side surface thereof. Moreover, the engaging protrusions 46 aare engaged with holes 31 g provided in the first plate 31. Accordingly,the friction plate 46 is non-rotatable relative to the first plate 31,but is rotatable relative to the annular disc plate 45.

As described above, the annular disc plate 45 and the friction plate 46,disposed on the second plate 32 side, are configured similarly to thosedisposed on the first plate 31 side. However, the cone spring 47 isattached between the second plate 32 and the friction plate 46 disposedon the second plate 32 side, while being compressed therebetween.

With the configuration described above, friction resistance (hysteresistorque) is generated between the friction plates 46 and the annular discplates 45 when the torsion springs 22 are compressed and extended byrelative rotation between the input-side rotor 20 and the output-siderotor 21. Likewise, a hysteresis torque is generated when relativerotation is produced between the output-side rotor 21 and theintermediate rotor 23 by compression and extension of the torsionsprings 22. In other words, the hysteresis generating mechanism 24includes a hysteresis generating part 24 a (see FIG. 4) for generating ahysteresis torque between the input-side rotor 20 and the output-siderotor 21 and a hysteresis generating part 24 b (see FIG. 3) for applyinga hysteresis torque to the intermediate rotor 23.

[Action]

Power, transmitted from the engine to the flywheel 4, is inputted to thedamper device 3 through the torque limiter device 2. In the damperdevice 3, the power is inputted to the first and second plates 31 and 32to which the friction disc 12 of the torque limiter device 2 is fixed,and is transmitted to the output-side rotor 21 through the torsionsprings 22. Then, the power is further transmitted from the output-siderotor 21 to the electric motor, the transmission, a power generator andso forth disposed on the output side.

Incidentally, in starting the engine, for instance, chances are that anexcessive torque is transmitted from the output side to the enginebecause the output side has a large inertia amount. In such a case, whentransmitted to the engine, the torque is limited in magnitude to apredetermined value or less by the torque limiter device 2.

In the damper device 3, when the power is transmitted to the torsionsprings 22 from the first and second plates 31 and 32, the torsionsprings 22 are compressed. Besides, the torsion springs 22 arerepeatedly compressed and extended by torque fluctuations. When thetorsion springs 22 are compressed and extended, torsion (displacement)is produced between the first and second plates 31 and 32 and theoutput-side rotor 21.

The hysteresis generating mechanism 24 is actuated by the torsionbetween the first and second plates 31 and 32 and the output-side rotor21, whereby a hysteresis torque is generated. Specifically, relativerotation is produced between the friction plates 46, fixed to the firstand second plates 31 and 32, and the annular disc plates 45 fixed to theoutput-side rotor 21. Hence, friction resistance is generatedtherebetween. Accordingly, the hysteresis torque is generated betweenthe first and second plates 31 and 32 and the output-side rotor 21.

Moreover, torsion is also produced between the output-side rotor 21 andthe intermediate rotor 23 by compression and extension of the torsionsprings 22. Because of this torsion, relative rotation is producedbetween the annular disc plates 45 fixed to the output-side rotor 21 andthe friction portions 41 b of the intermediate rotor 23, wherebyfriction resistance is generated therebetween. Accordingly, a hysteresistorque is generated between the output-side rotor 21 and theintermediate rotor 23.

Chances are that, depending on the rotational speed of the engine, theintermediate rotor 23 greatly vibrates due to resonance. However, in thepresent preferred embodiment, the intermediate rotor 23 can be inhibitedfrom vibrating with a large amplitude due to resonance by the hysteresistorque generated between the output-side rotor 21 and the intermediaterotor 23.

FIG. 7 shows the magnitude of vibration of the intermediate rotor 23. InFIG. 7, broken line m indicates a condition in which a hysteresis torqueis not applied to the intermediate rotor 23, whereas solid line Mindicates a condition in which a hysteresis torque is applied to theintermediate rotor 23. As is obvious from FIG. 7, vibration due toresonance can be inhibited in magnitude by applying a hysteresis torqueto the intermediate rotor 23.

It should be noted that when the angle of torsion is increased betweenthe first and second plates 31 and 32 and both the output-side rotor 21and the intermediate rotor 23, one end surface of each bent portion 31 cof the first plate 31 and that of each stopper portion 41 e of theintermediate rotor 23 make contact with each other. Because of this, thetorsion angle between the first and second plates 31 and 32 and both theoutput-side rotor 21 and the intermediate rotor 23 can be inhibited fromreaching a predetermined angle or greater. Therefore, it is possible toavoid a situation that excessive stress acts on the torsion springs 22.

[Other Preferred Embodiments]

The present invention is not limited to the preferred embodimentdescribed above, and a variety of changes or modifications can be madewithout departing from the scope of the present invention.

In the aforementioned preferred embodiment, the intermediate flanges 41of the intermediate rotor 23 and the bent portions 31 c of the firstplate 31 are configured to make contact with each other so as to composea stopper mechanism. Alternatively, the flanges 36 of the output-siderotor 21 and the bent portions 31 c can be configured to make contactwith each other so as to compose a stopper mechanism.

REFERENCE SIGNS LIST

-   3 Damper device-   20 Input-side rotor-   21 Output-side rotor-   22 Torsion spring-   23 Intermediate rotor-   31 First plate-   31 b First window portion (first holding portion)-   31 c Bent portion-   31 d Fixation portion-   31 f Rivet swaging hole (work hole)-   32 Second plate-   32 b Second window portion (second holding portion)-   33 Rivet (fixation member)-   35 Hub (annular portion)-   36 Flange-   36 d Rivet swaging hole (work hole)

What is claimed is:
 1. A damper device comprising: a first rotor disposed to be rotatable; a second rotor rotatable relative to the first rotor; and a plurality of elastic members configured to elastically couple the first rotor and the second rotor in a circumferential direction, wherein the first rotor includes a first plate and a second plate, the first and second plates each having a disc shape, the first and second plates axially opposed to each other, the first and second plates fixed to be immovable in both axial and circumferential directions, the first plate includes a plurality of first holding portions and a plurality of bent portions, the plurality of first holding portions holding the plurality of elastic members, the plurality of bent portions provided on an outer peripheral end of the first plate, the plurality of bent portions bent toward the second plate, and the second plate includes a plurality of second holding portions, the plurality of second holding portions holding the plurality of elastic members together with the plurality of first holding portions.
 2. The damper device according to claim 1, wherein the second rotor is disposed axially between the first plate and the second plate.
 3. The damper device according to claim 1, further comprising: a third rotor configured to actuate at least two of the plurality of elastic members in series, the third rotor rotatable relative to the first rotor and the second rotor, wherein the third rotor is further configured to make contact in part with at least one of circumferential end surfaces of the plurality of bent portions.
 4. The damper device according to claim 3, wherein the third rotor includes an annular portion, and a flange configured to actuate the at least two of the plurality of elastic members in series, the flange provided to extend radially outward from the annular portion, and the first plate and the third rotor are restricted from being rotated relative to each other when the flange makes contact at an outer peripheral part thereof with one of the circumferential end surfaces of the plurality of bent portions.
 5. The damper device according to claim 1, wherein the first plate includes a fixation portion, the fixation portion formed by bending a distal end of each of the plurality of bent portions radially inward, the damper device further comprising: a fixation member fixing the fixation portion and the second plate to each other.
 6. The damper device according to claim 5, wherein each of the first plate and the second rotor includes a work hole configured to fix the fixation portion and the second plate to each other by the fixation member.
 7. The damper device according to claim 1, wherein the second rotor includes a hub having a tubular shape, and each of the first and second plates includes a hole in a center part thereof, the first and second plates radially positioned by an outer peripheral surface of the hub and an inner peripheral surface of the hole of the each of the first and second plates. 